DOES EVOLUTION QUALIFY AS A SCIENTIFIC PRINCIPLE?

Ariel A. Roth

The Humanist, an official publication of the American
Humanist Association and the American Ethical Union, recently (January/February 1977)
published a statement affirming evolution as a principle of science. The statement, signed
by 163 scholars, most of whom are biologists in leading universities of the United States,
was prepared for distribution to major public school districts in the United States. Among
its sponsors are such notables as Isaac Asimov, Linus Pauling, and George Gaylord Simpson.
The statement points out that "all known forms of life including
human beings developed by a lengthy process of evolution." This broad perspective on
evolution is what Kerkut (1960, p. 157) calls the "general theory of evolution,"
in contrast to the "special theory of evolution" which deals with small
variations in organisms such as have been observed in nature and the laboratory. The
statement in the Humanist also indicates that the principle of biological
evolution meets "exceptionally well" the criteria demanded by science of being
"firmly established ... on rigorous evidence" and that in recent
years more confirmation of the principle of natural selection and adaptation as proposed
by Darwin and Wallace has continued to accumulate. The statement further asserts that
"creationism is not scientific," while evolution is "strictly
scientific."
On the other hand there has been an ongoing debate within the
scientific community, largely among individuals who believe in evolution, about the
validity of evolution as a scientific principle. The statement published in the Humanist
suggests that under the pressure of current criticism leveled at evolution, basic
scientific values may be overlooked or given secondary place over other factors.
Much of the debate regarding the validity of evolution revolves around
the elementary notion that science explains things on the basis of cause and effect.
Simply stated, given certain conditions, certain results can be expected. This feature
gives science its predictive qualities. For instance the statement "a magnet attracts
iron" can be tested and used to predict what will happen when the two are near each
other.
Hans Reichenbach in The Rise of Scientific Philosophy (1951,
p. 89) emphasizes the necessity of a predictive quality for science:

A mere report of relations observed in the past cannot be called knowledge;
if knowledge is to reveal objective relations of physical objects, it must include
reliable predictions. A radical empiricism, therefore, denies the possibility of
knowledge.

The concept of predictability and subsequent testability has prompted the noted
scientific philosopher Karl Popper to further emphasize that if an explanation cannot be
adequately tested, it is not scientific. The concept must be testable (i.e., falsifiable)
to qualify. Any kind of explanation will not do; it must be amenable to a testing process.
If it survives testing, it can qualify. In our magnet example, we might propose that
objects of only a certain color (and not a magnet) attract iron. If a red magnet were
found to work, we could further test the notion by using a wooden block of the same color
as the magnet and thus disprove the color theory. Popper in his book The Logic of
Scientific Discovery (1968, p. 40) is emphatic on the matter of falsification. He
states:

But I shall certainly admit a system as empirical or scientific only if it
is capable of being tested by experience. These considerations suggest that not the verifiability
but the falsifiability of a system to be taken as a criterion of demarcation.

The idea that a genuine scientific idea must have the consistency
that gives it predictive value, and the potential for falsification, has received a great
deal of attention during the past few years among scientific philosophers and
evolutionists. There is very little disagreement with this aspect of science as enunciated
by Popper, and there is genuine concern as to how to apply this principle to the theory of
evolution. The unrepeatable or untestable events postulated for evolution are not amenable
to evaluation on the basis of consistency and prediction. Thus the concept of evolution as
a principle of science is being questioned at a most fundamental level. Does it really
qualify as a scientific principle? Some examples of deficiencies follow.
The concept of natural selection by survival of the fittest is the
basic evolutionary mechanism. This concept does not qualify as a scientific principle,
since fitness is equivalent to survival. Here we have a case of circular reasoning; no
consistency or predictive value can be tested. According to this idea, organisms have
survived through the evolutionary process because they are better fit, and the way one
tells they are better fit is that they survive. A number of evolutionary scholars have
labeled the principle of survival of the fittest a tautology (e.g., Waddington 1957, Eden
1967, Peters 1976). Popper (1963) attacks the unfalsifiable nature of the concept and
concludes:

If, more especially, we accept that statistical definition of fitness which
defines fitness by actual survival, then the survival of the fittest becomes tautological,
and irrefutable.

The concept of survival of the fittest of itself does not
necessarily imply any evolution. Would not the fittest survive, whether they evolved or
were created? The noted evolutionist Mayr (1976, p.3) speaks of "an all-powerful
natural selection." Platnick (1977) wonders if there is any difference in this kind
of explanation as compared to that of an all-powerful Creator.
Some evolutionary biologists are of the opinion that it is not
necessarily the fittest that survive through the evolutionary process, but those that are
best adapted to the requirements of evolution. Others have emphasized that survival of the
organism is not as important as its fecundity. In both cases the problem of predictability
remains. In a symposium volume celebrating 100 years of Darwinism the prominent geneticist
Waddington (1960, p. 385) evaluates the matter of fecundity. He states:

Natural selection, which was at first considered as though it were a
hypothesis that was in need of experimental or observational confirmation, turns out on
closer inspection to be a tautology, a statement of inevitable although previously
unrecognized relation. It states that the fittest individuals in a population (defined as
those which leave most offspring) will leave most offspring.

Another problem associated with the untestability of evolutionary
theory is that the theory explains too much. Grene (1959) points out that "whatever
might at first sight appear as evidence against the theory is assimilated by redefinition
into the theory." Evolutionary theory is broad enough to accommodate almost any data
that may be applied. Two ecologists Birch and Ehrlich (1967) emphasize this. They state:

Our theory of evolution has become, as Popper described, one which cannot be
refuted by any possible observations. Every conceivable observation can be fitted into it.
It is thus 'outside of empirical science' but not necessarily false. No one can think of
ways in which to test it.

No matter what is observed, there usually is an appropriate
evolutionary explanation for it. If an organ or organism develops, it has positive
survival value; if it degenerates, it has negative survival value. If a complex biological
system appears suddenly, it is due to preadaptation. "Living fossils"
(contemporary representatives of organisms expected to be extinct) survive because the
environment did not change. If the environment changes and an evolutionary lineage
survives, it is due to adaptation. If the lineage dies, it is because the environment
changed too much, etc. Hence the concept cannot be falsified. Platnick (1977) states that
this type of situation "makes of evolutionary biologists spinners of tales, bedtime
storytellers, instead of empirical investigators."
A few scientists (e.g., Williams 1970, 1973, Ball 1975, Ferguson 1976)
have tried to show that evolutionary theory can predict. Their attempts, however, are
concerned with the small changes of the special theory of evolution instead of the general
one which is at issue and which is the main subject of the declaration published in the Humanist.
These small changes do not prove large ones as Grene (1959) points out:

By what right are we to extrapolate the pattern by which colour or other
such superficial characters are governed to the origin of species, let alone of classes,
orders, phyla of living organisms?

The question of the testability of the general theory of evolution remains.
Basic textbooks of biology usually illustrate evolution using the
concept of homologous structures. Here we have another example of circular reasoning that
would not pass the prediction test for science. Homologous structures are defined as
comparable parts of different life forms that have a common evolutionary origin. The
forelimbs of a salamander, crocodile, bird, bat, whale, mole and man all have the same
basic bone structure and are considered homologous. Similarity does not necessarily imply
evolution. A student commenting to an evolutionary professor put it aptly: "They find
a muscle in an animal and give it a name; in another animal they find a muscle in a
similar position and give it the same name and then call it evolution." Darwin
himself used the argument of similarity of structure to support evolution.

Lee (1969) points out that the argument is logically invalid:

He [Darwin] argued that morphological similarities were due to
common descent and yet offered no further really acceptable evidence for common descent
save morphological similarities. A circular piece of reasoning if there ever was one.

Hull (1967) makes the same complaint:

It is tautological to say that homologous resemblances are indicative of
common line of descent, since by definition homologous resemblances are those resemblances
due to common line of descent.

The same difficulty reappears when evolutionists attempt to classify
living and fossil organisms so that their evolutionary relationships are revealed. One
might select, for example, the group of invertebrates which most closely resembles the
chordates and place the two groups near each other in a classification scheme. The
classification is then often used as evidence for an evolutionary relationship.
Several widely divergent schools of thought have developed regarding
the kinds of characteristics that are most important in determining evolutionary
relationships. As a result opinions as to whether Popper's criteria of falsifiability can
be satisfied also differ widely (e.g., Bock 1973, Wiley 1975). Perhaps the soundest
conclusion expressed by a number of scholars is that from a practical standpoint the
process of evolution is too complex and past events too unknown to permit a meaningful
reconstruction of evolutionary phylogenetic patterns (Manser 1965, Barker 1969, Lee 1969,
Platnick 1977). Orians (1973) and Slobodkin (1968) admit it is very difficult. An
alternative is to adopt the view expressed by the prominent evolutionist Ernst Mayr (1976,
p. 411) that classification of organisms is an "art." This would remove the
problem altogether from the arena of science.
This brings us to another point: a number of scientists and scientific
philosophers in attempting to reconcile the lack of rigor in evolutionary theory compared
to current scientific standards have proposed that evolution be treated differently. This,
of course, tends to alienate it from science and from being a "principle of
science" as proposed in the Humanist statement. Such views have been
proposed by Beckner (1959), Scriven (1959), Smart (1963), and Manser (1965), while Barker
(1969) and Flew (1966) propose that evolution is more closely related to historical
studies than to typical science. Ruse (1973) on the other hand suggests that evolutionary
events are subject to the same scientific principles that apply to most of science.
Platnick (1977) in the journal Systematic Zoology is still more emphatic:

Evolutionary biologists have a choice to make: either we agree with Mayr
that narrative explanations are the name of the game, and continue drifting away from the
rest of biology into an area ruled only by authority and consensus, or we insist that
whenever possible our explanations be testable and potentially falsifiable and that
evolutionary biology rejoin the scientific community at large.

The concept of creation does not appear to meet the criterion of
falsifiability any better than evolution. Science is not at its best when dealing with
unique past events, whether these be considered as evolution or creation. Therefore it is
surprising to find a statement signed by more than 120 scientists stating that creationism
is "a purely religious view" while evolution is labeled as "strictly
scientific."
The controversy over whether or not evolution is a scientific principle
has reached beyond the scientific community. In his article entitled "Darwin's
Mistake," published in Harper's Magazine, Bethell (1976) states his belief
that Darwin's theory "is on the verge of collapse." The jurist Macbeth (1971) in
his book Darwin Retried presents a long list of illogical arguments employed in
support of evolution. He does not defend creation, yet states that "Darwinism itself
has become a religion" (p. 126).
The statement in the Humanist affirming evolution as a
principle of science has the support of many influential scientists; yet a review of the
literature of both science and the philosophy of science reveals significant doubt
regarding its validity. In view of this, it is sobering to think that so many scientists
should affirm, in a public statement to be sent to public schools, that evolution is a
principle of science that meets "exceptionally well" the criteria of science
which are based on "rigorous evidence." Apparently this is not the case at all.
Evolutionists need to re-examine their thinking and re-evaluate their claims.